1. Field of the Invention
The present invention relates to a motor, and more particularly, to a motor and a washing machine including the motor.
2. Description of the Related Art
A motor is a machine that converts electrical energy to mechanical energy, and is often referred to as a drive unit. A motor works on the principle of electromagnetic induction. Although most motors generate force in a rotational manner, some generate force linearly. Motors are categorized into direct current (DC) motors and alternating current (AC) motors, depending on their power source.
A washing machine is an apparatus that employs a motor described above as its main driving source, and uses detergent mixed into water to wash laundry and remove impurities therefrom over the course of wash, rinse, and spin cycles. A washing machine has a mechanical unit that the energy of the motor or drive unit to wash laundry, a control unit that controls the wash course, and a water supplying and draining device to fill and drain the washing compartment. Washing machines being used today can largely be divided into drum-type, agitator-type, and pulsator-type washing machines.
According to their projected load, the above-described motors uses permanent magnets to which current is applied, forming a predetermined phase angle to rotate the motor based on Fleming's Left-Hand Rule. To generate maximum torque during the wash cycle, the phases of the current are controlled to be in phase with phases of counter electromotive force, and to generate high speed in the spin cycle, the phases of current are controlled to precede the phases of counter electromotive force.
A large quantity of permanent magnets is used in motors according to the related art. Because a permanent magnet is an expensive material by weight, the manufacturing cost of a motor increases.
Also, because motors according to the related art use rotor frames that are press manufactured thin steel plates, the frames have low rigidity and reduced concentricity and roundness. Therefore, vibration and noise are pronounced during motor operation.